Dynamical Study of Photoexcited States in Semiconductors by Means of Femtosecond Pump-and-Probe Spectroscopy

飞秒泵浦-探针光谱应用于高激发态CdSe中非平衡电子的观察。在50 fs内观察到电子的非平衡分布。ii型AlGaAs-AlAs量子阱中的激子-空穴碰撞>用时间分辨简并四波混频方法测量了激子-空穴碰撞率。激子的相松弛主要是由激子与长寿命空穴的碰撞引起的。在飞秒泵浦-探针实验中，观察到BiI_3晶格晶体中间接吸收边缘附近的共振相干晶格振动。相干横向光学晶格振动周期为300 fs，持续100多个周期。<万尼尔激子和激子极化子的量子拍>在ZnP_2中观察到万尼尔激子和激子极化子的量子拍。群颤源于主量子数n为2、3和4的万尼尔激子。在n =1共振周围，由于上下极化子的干涉，也观察到极化子的量子拍。

<Observation of nonequilibrium electrons in CdSe> Femtosecond pump-and-probe spectroscopy was applied to highly excited CdSe. Nonequilibrium distribution of electrons was observed for 50 fs. <Exciton-hole collision in type-II AlGaAs-AlAs quantum wells> Exciton-hole collision rate was measured by means of time-resolved degenerate four-wave mixing. Phase relaxation of excitons is dominated by the collision between the excitons and long-lived holes. <Observation of coherent optical phonons in BiI_3> Resonant coherent lattice vibrations in the vicinity of the indirect absorption edge in a BiI_3 lattice crystal are observed in a femtosecond pump-and-probe experiment. The coherent transverse optical lattice vibration, which has a period of 300 fs, continues for more than 100 cycles. <Quantum beats of Wannier excitons and excitonic polaritons> Quantum beats of Wannier excitons and excitonic polaritons were observed in ZnP_2. Qunatum beat originates from Wannier excitons whose principal quantum numbers n are 2,3 and 4. Polariton quantum beat was also observed as a result of interference of both upper and lower polaritons around the n =1 resonance.